Mustache

Ktor allows you to use Mustache templates as views within your application by installing the Mustache plugin.

Add dependencies

To use Mustache, you need to include the ktor-server-mustache artifact in the build script:

implementation("io.ktor:ktor-server-mustache:$ktor_version")

implementation "io.ktor:ktor-server-mustache:$ktor_version"

        
                    <dependency>
                        <groupId>io.ktor</groupId>
                        <artifactId>ktor-server-mustache-jvm</artifactId>
                        <version>${ktor_version}</version>
                    </dependency>
                    
        

Install Mustache

To install the Mustache plugin to the application, pass it to the install function in the specified module. The code snippets below show how to install Mustache...

... inside the embeddedServer function call.
... inside the explicitly defined module, which is an extension function of the Application class.

                    import io.ktor.server.engine.*
                    import io.ktor.server.netty.*
                    import io.ktor.server.application.*
                    import io.ktor.server.mustache.*

                    fun main() {
                        embeddedServer(Netty, port = 8080) {
                            install(Mustache)
                            // ...
                        }.start(wait = true)
                    }
                

                    import io.ktor.server.application.*
                    import io.ktor.server.mustache.*
                    // ...
                    fun Application.module() {
                        install(Mustache)
                        // ...
                    }
                

Inside the install block, you can configure the MustacheFactory for loading Mustache templates.

Configure Mustache

Configure template loading

To load templates, you need to assign the MustacheFactory to the mustacheFactory property. For example, the code snippet below enables Ktor to look up templates in the templates package relative to the current classpath:

import com.github.mustachejava.DefaultMustacheFactory
import io.ktor.server.application.*
import io.ktor.server.mustache.Mustache
import io.ktor.server.mustache.MustacheContent

fun Application.module() {
    install(Mustache) {
        mustacheFactory = DefaultMustacheFactory("templates")
    }
}

Send a template in response

Imagine you have the index.hbs template in resources/templates:

<html>
    <body>
        <h1>Hello, {{user.name}}</h1>
    </body>
</html>

A data model for a user looks as follows:

data class User(val id: Int, val name: String)

To use the template for the specified route, pass MustacheContent to the call.respond method in the following way:

        get("/index") {
            val sampleUser = User(1, "John")
            call.respond(MustacheContent("index.hbs", mapOf("user" to sampleUser)))
        }

Last modified: 02 April 2024